Combines for harvesting various crops have long included conveyors for moving crop material from cutting or pickup apparatus upwardly and rearwardly along a conveyor surface to an auger or other means for feeding the material into threshing apparatus.
Such conveyors typically include a fixed conveyor surface tilted upwardly toward the threshing apparatus, at least two (often three) endless chains driven by sprockets beside the conveyor surface and having parallel reaches extending along the surface, and a series of elongated carriers secured at their opposite ends to a pair of chains and extending across and above the surface, usually in close proximity to it. Such elongated carriers are driven along the conveyor surface by the chains and serve as means to carry crop material toward the threshing apparatus. The conveyor surface is usually along the lower reaches of the endless chains, and crop material is moved in an undershot manner.
Examples of such prior combine conveyors are disclosed in the following U.S. Pat. Nos. : 3,939,847 (Straeter); 4,498,483 (Dammann); 3,967,719 (Kloefkorn et al.); 3,780,851 (Bichel et al.); and 4,227,538 (Long et al.).
Prior combine conveyors of the type described have a number of problems and shortcomings. They are often prone to malfunctions caused by part breakage and deformation. This is caused by the extreme forces and loads applied to them. The parts which break most often include the elongated carriers themselves and the connectors securing them to the chains.
Extreme loads, shocks and forces on such parts are caused by a variety of conditions. Among these are: overloading of crops on the conveyor, particularly when accompanied by an excessive wedging and/or build-up of crops between parts; encountering obstacles such as stones while the conveyor is moving; and variations in chain height (between the two chains supporting an elongated carrier) such as when one of the chains rides over a sprocket tooth. These conditions are not at all uncommon in combine operations.
The extreme forces and shock loads are applied in various directions -- sometimes as side loads, sometimes as twisting loads. They can cause permanent deformation of metal parts, including the elongated carriers themselves, immediate breakage of connectors in some cases, stress cracks which eventually lead to breakage in other cases, and all too often catastrophic failures of the equipment when it is needed the most.
Another problem with certain prior combine conveyors is their tendency toward excessive conveyor back feed, that is, the inability of the conveyor to more completely release the crop material to the auger above, particularly when there is a heavy flow of such material. In such cases, some crop material is carried back down the conveyor along the upper reach of the chains, the crop material being held against the back portions of the elongated carriers.
In response to the considerable problems related to stress and breakage, there has been a tendency to build sturdier and stouter elongated carriers and chain-mounting devices. This is typically done by adding material thickness and/or by configuring the elongated carriers to add structural strength. These efforts in some cases may tend to forestall problems, while in other cases they may result in more difficult clogs and jams and forces with all the attendant stress and failure of material.
There has long been a clear need for an improved combine conveyor.